True. Solid nonmetals are usually brittle with little to no luster (shine). For example, phosphorous and carbon are dull, brittle solids that do not conduct thermal energy or electricity.
Nonmetals are found to the right of the zigzag line that cuts diagonally from the left to the right within the p- block of the periodic table. Nonmetals tend to have high ionization energies and electronegativities. Thus, nonmetals tend to be receivers of electrons.
Metals, on the other hand, are found to the left of the zigzag line. The delocalized electrons of transition metals make such elements excelled conductors of thermal energy and electricity. Metals are ductile, malleable, hard, and have a high luster. Metals have low ionization energies and electronegativities. Thus, metals tend to be donators of electrons.